1. Field of the Invention
The present invention relates to a steering device of the type which carries out tilt/telescopic adjustments using two clamping/fastening bolts disposed at front and back locations, and relates to a steering position adjustment device, which can stabilize and improve operations of the tilt/telescopic adjustments, and can improve the operating feeling of the lever operation.
2. Description of the Related Art
As for a steering column comprising a tilt/telescopic adjustment device, there have existed for some time those of the type in which a fixed bracket and a movable bracket are supported by a front-back dual-location tightening device, and the fixed bracket and movable bracket are tightened and loosened by tightening and loosening the screws of the tightening device.
This tilt/telescopic adjustment device is configured such that, when an operating lever is pivoted in a loosening direction, a tightening device of the operating lever and a tightening device of an arm member are set in a linked state by a linking member. As for the tightening device, since only the intermediate shaft portion is restrained by a locking member of the head portion of the tightening device on the opposite side to the operating lever and arm member, and the shaft-end of the tightening device on the side of the operating lever and arm member is in a free state in contrast to the fixed state of the opposite side thereof resulting from the restraining of the end, the tightening device will arbitrarily move in any direction, upward or downward, forward or backward.
In the rotating operation of the operating lever, the shafts of the operating lever and arm member fluctuate in accordance with the movement and twisting of the shafts, the tightening force is dispersed and freed due to the movement, and, accordingly, there is a danger that an insufficient retaining force will be achieved, and further, there are times when tightening cannot be made stable, and the operating feeling is impaired.
The irregular movement of the operating lever and arm member tilt/telescopic adjustments cannot be suppressed by a simple structure. Furthermore, in the above-mentioned example, the tightening devices of both the operating lever and the arm member are inserted and positioned inside intersecting long holes comprising a transverse slot and a vertical slot, but the irregular movement is not limited thereto, and the same problem exists with a tilt/telescopic adjustment device in which the tilt/telescopic steering operating lever, arm member and linking member are tightened at two locations.
For example, a firm retaining force can be achieved, the tightening force can be made stable, and the operating feeling of lever operation can be made extremely better without moving the operating lever and arm member at the tightening time. Further, a fixed structure, which links one operating lever and arm member to one bracket via a linking member, and which provides a dual-location tightening device, has been known to be capable of being tightened by a rotating operation of a lever, but, a problem persists in that although multiple dual-location tightening devices on one bracket provide more secure fastening than with a single tightening device type, the operational stability and operating feeling cannot be easily improved.
Accordingly, as a result of the inventors"" studious research to solve the above-mentioned problems, the present invention is accomplished to provide a steering position adjustment device comprising a fixed bracket; a movable bracket, to which a steering column is attached; two sets of through holes including front and back through hole sets, which are formed in the fixed bracket and movable bracket, respectively, and at least one set of which includes a transverse slot and a vertical slot intersecting each other; two clamping/fastening bolts which are inserted through these through holes; an arm member, which screws on one of the clamping/fastening bolts; an operating lever member; a retaining member for holding the clamping/fastening bolts, which are screwed in the arm member and operating lever member, respectively, at the centers of turning, so as to be spaced by a predetermined distance; and a linking member, which is pivotally linked to the arm member and operating lever member, so that support is provided by the through holes formed at two locations, and by the fastening of the fixed and movable brackets by the two clamping/fastening bolts inserted through the through holes at the respective two locations. In this arrangement, it is possible to provide positional adjustment on a steering column having a stopper mechanism, which is capable of stabilizing, at a suitable position, a tightening position and a loosening position of the operating lever, which has an arm linked via the linking member, irregardless of the movement position of the movable bracket relative to the fixed bracket, thus solving the above-mentioned problems.